Help needed to Write fist hello world operating system in pen drive.

I am not much knew to assembly language. I worked on it in my college days. But now i am again starting it after a gap of two years. Lot of things are gone. Except the interest in the simplicity in assembly language. Now i am trying to make a very small operating system of simply printing hello world. I am using pen drive in place of floppy here. the program i am using is
;----------------------------------------------------------------------
; Simple boot program that prints the letter 'H'
; and then hangs
; Joel Gompert 2001
;
; Disclaimer: I am not responsible for any results of the use of the contents
; of this file
;----------------------------------------------------------------------
org 0x7c ; This is where BIOS loads the bootloader

; --------------------------------------------
; Boot program code begins here
; --------------------------------------------
; boot code begins at 0x003E
begin:
mov ah, 0x0e ; Function to print a character to the screen
mov al, 'H' ; Which character to print
mov bl, 7 ; color/style to use for the character
int 0x10 ; print the character

Firstly I'd like to Organize the code by using code tags and make it more readable..

Code: asm

;----------------------------------------------------------------------; Simple boot program that prints the letter 'H'; and then hangs; Joel Gompert 2001;; Disclaimer: I am not responsible for any results of the use of the contents; of this file;----------------------------------------------------------------------org 0x7c ; This is where BIOS loads the bootloader

; --------------------------------------------; Boot program code begins here; --------------------------------------------; boot code begins at 0x003Ebegin:movah, 0x0e ; Function to print a character to the screenmoval, 'H'; Which character to printmovbl, 7; color/style to use for the characterint 0x10 ; print the character